1. Field of the Invention
The invention relates to a tapered roller bearing, and in particular, to a tapered roller bearing that supplies a lubricant in a space where tapered rollers roll.
2. Description of the Related Art
A tapered roller bearing includes an outer ring, an inner ring, a plurality of tapered rollers, and a cage. The tapered rollers are arranged such that a central axis of each roller is inclined with respect to a central axis of the tapered roller bearing. At least a part of a large-diameter bottom face (hereinafter referred to as a roller large end face) of the tapered roller is arranged outward of a small-diameter bottom face (hereinafter referred to as a roller small end face) in a radial direction of the bearing.
The tapered roller bearing characteristically needs, for example, to (1) offer enhanced resistance to seizure between the roller large end faces of the tapered rollers and a surface of the inner ring that contacts the roller large end faces (hereinafter referred to as a cone back face rib surface) and to (2) reduce wear between each tapered roller and a corresponding pocket surface of the cage (an inner surface of each pocket formed in the cage and in which the corresponding tapered roller is housed). As such a tapered roller bearing, a tapered roller bearing is known in which a lubricant holding member is attached to the outer ring so that a lubricant can be held in a space between the lubricant holding member and the outer ring (for example, Japanese Patent Application Publication No. 2008-057791 (JP 2008-057791 A)).
The lubricant may be contaminated by foreign matter such as external dust or abrasion powder from the tapered rollers. When the lubricant containing the foreign matter infiltrates in between the tapered roller and a raceway surface, noise may be generated by the foreign matter when one of the inner ring and the outer ring of the tapered roller bearing rotates with respect to the other, and due to the foreign matter, the life of the bearing may be shortened.